Biological oxidation of ferrous sulphate by Thiobacillus ferrooxidans: a review on the kinetic aspects

Ferrous sulphate oxidation using thiobacillus ferrooxidans: a review

Preface Section I - Fundamentals, microorganisms and mechanisms Microorganisms involved in bioleaching and nucleic acid-based molecular methods for their identification and quantification Axel Schippers Mechanisms and biochemical fundamentals of bacterial metal sulfide oxidation Thore Rodwerder and Wolfgang Sand Electrochemical techniques used to study bacterial-metal sulfides interactions Denise Bevilaqua, Heloisa A. Acciari, Assis V. Benedetti and Oswaldo Garcia Jr Electrochemical mechanism of leaching. Influence of the presence of catalytic ions and bacteria Antonio Ballester, Maria Luisa Blazquez, Felisa Gonzalez and Jesus A. Munoz Recovery of zinc, nickel, cobalt and other metals by bioleaching Marisa R. Viera, Cristina M. Pogliani and Edgardo R. Donati Bioleaching of metals in neutral and slightly alkaline environment Aleksandra Sklodowska and Renata Matlakowska Section II - Bioreactors and Bioheaps Bioleaching of sulfide minerals in continuous stirred tanks Dominique Henri Roger Morin Bioreactor design fundamentals and their application to gold mining Fernando Acevedo and Juan Carlos Gentina Air-lift reactors: characterization and applications in biohydrometallurgy Alejandra Giaveno, Laura Lavalle, Patricia Chiacchiarini and Edgardo R. Donati Principles, mechanisms and dynamics of chalcocite heap bioleaching Jochen Petersen and David G. Dixon Section III - Genetics and Molecular Biology The use of bioinformatics and genome biology to advance our understanding of bioleaching microorganisms Raquel Quatrini, Jorge Valdes, Eugenia Jedlicki and David S. Holmes Proteomics and metaproteomics applied to biomining microorganisms Carlos A. Jerez Cell-cell communication in bacteria: A promising new approach to improve bioleaching efficiency? Susana Valenzuela,Alvaro Banderas, Carlos A. Jerez and Nicolas Guiliani Section IV - Other Applications Bioflotation and bioflocculation of relevance to minerals Bioprocessing K. Hanumantha Rao and S. Subramanian Desulphurization of gaseous emissions containing hydrogen sulfide Jose Manuel Gomez and Domingo Cantero Index

Microbial Processing of Metal Sulfides

Ferrous and ferric phosphate crystalline compounds and glasses were studied using Raman spectroscopy. A comparison of the spectra from crystalline and glassy ortho-, pyro-, and metaphosphates indicates that similar phosphate anions constitute the structures of the respective materials, and some information about the compositional dependence of the phosphate-site distributions in the glasses can be gleaned from relative peak intensities. A correlation exists between the average P–O bond distance and the Raman peak frequencies in the crystalline compounds, and this correlation is used to provide information about the structures of the iron phosphate glasses. For example, the average P–O bond distance is estimated to decrease from about 1.57 A for iron metaphosphate glasses (O/P∼3.0) to 1.54 A for iron orthophosphate glasses (O/P∼4.0). These bond distances are in good agreement with those reported from diffraction studies of similar glasses.

A Raman Study of Iron–Phosphate Crystalline Compounds and Glasses

Jarosite-group compounds [ M Fe 3 (SO 4 ) 2 (OH) 6 : argentojarosite ( M + = Ag + ), jarosite ( M + = K + ), ammoniojarosite ( M + = NH 4 + )] were synthesized by supplying Fe 3+ ions in three different ways: biological oxidation of Fe 2+ ions by T. ferrooxidans (biological products), chemical oxidation of Fe 2+ ions by slow addition of H 2 O 2 (chemical products 1), and chemical oxidation by rapid addition of H 2 O 2 (chemical products 2). These were characterized by XRD, FTIR, chemical analysis and SEM; as well, the morphological features were compared with those formed by the hydrothermal method (standard substances). The jarosite-group compounds so synthesized do not contain crystalline by-products, as revealed by XRD, but the order of purity inferred from IR spectra, which is determined by the intensity of specific peaks, was found to be dependent on the method of preparation and is independent of the jarosite species; the order was found to be standard substances > chemical products 2 > chemical products 1 > biological products. Two main factors were found to affect the morphology, the method and rate of supply of Fe 3+ ions to the system and the nature of the monovalent cations, which determine the intrinsic rate of formation under given conditions. Where Fe 3+ ions are present in the system from the beginning, the order of rate of formation is confirmed to be argentojarosite > jarosite > ammoniojarosite at 30°C. Morphological features of jarosite-group phases formed by the biological method were rendered distinguishable by the effect of extracellular substances. Morphological information is useful to distinguish the mode of occurrence of jarosite-group phases in natural samples, since it may be difficult to do so by other analytical techniques, such as XRD, FTIR, Raman spectroscopy and chemical analysis.

MORPHOLOGY OF JAROSITE-GROUP COMPOUNDS PRECIPITATED FROM BIOLOGICALLY AND CHEMICALLY OXIDIZED Fe IONS

A packed-bed bioreactor with activated-carbon particles as a carrier matrix material inoculated with Thiobacillus ferrooxidans was operated at a pH of 1.35 to 1.5 to convert ferrous sulfate to ferric sulfate. Despite the low operating pH, trace amounts of precipitates were produced in both the reactor and the oxidized effluent. X-ray diffraction and chemical analyses indicated that the precipitates were well-ordered potassium jarosite. The chemical analyses also revealed a relative deficiency of Fe and an excess of S in the reactor sample compared with the theoretical composition of potassium jarosite.

Characterization of Jarosite Formed upon Bacterial Oxidation of Ferrous Sulfate in a Packed-Bed Reactor.

Thiobacillus ferrooxidans was used in fixed-film bioreactors to oxidize ferrous sulfate to ferric sulfate. Glass beads, ion-exchange resin, and activated-carbon particles were tested as support matrix materials. Activated carbon was tested in both a packed-bed bioreactor and a fluidized-bed bioreactor; the other matrix materials were used in packed-bed reactors. Activated carbon displayed the most suitable characteristics for use as a support matrix of T. ferrooxidans fixed-film formation. The reactors were operated within a pH range of 1.35 to 1.5, which effectively reduced the amount of ferric iron precipitation and eliminated diffusion control of mass transfer due to precipitation. The activated-carbon packed-bed reactor displayed the most favorable biomass holdup and kinetic performance related to ferrous sulfate oxidation. The fastest kinetic performance achieved with the activated-carbon packed-bed bioreactor was 78 g of Fe2+ oxidized per liter per h (1,400 mmol of Fe2+ oxidized per liter per h) at a true dilution rate of 40/h, which represents a hydraulic retention time of 1.5 min.

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Fast Kinetics of Fe2+ Oxidation in Packed-Bed Reactors

Thiobacillus ferrooxidans was used in fixed-film bioreactors to oxidize ferrous iron to ferric iron. The test support matrix materials included activated carbon particles, glass beads, and ion-exchange resin particles. The experimental systems included a fluidized bed approach, which was evaluated with activated carbon only, and a packed bed approach which was tested with each of the support matrix materials. The colonization of the matrix surface was examined with scanning electron microscopy. There were contrasting differences in the bacterial colonization and accumulation of Fe(III) precipitates on the matrix surface among the test materials. The packed bed activated carbon bioreactor displayed the fastest kinetics and the highest amount of cell sorption as well as the roughest and most porous matrix surface.

Scanning electron microscopic examination of Thiobacillus ferrooxidans on different support matrix materials in packed bed and fluidized bed bioreactors

Sergei I. Grishin

Papers

Characterization of Jarosite Formed upon Bacterial Oxidation of Ferrous Sulfate in a Packed-Bed Reactor.

Fast Kinetics of Fe2+ Oxidation in Packed-Bed Reactors

Scanning electron microscopic examination of Thiobacillus ferrooxidans on different support matrix materials in packed bed and fluidized bed bioreactors